[Federal Register Volume 59, Number 140 (Friday, July 22, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-17766]


[[Page Unknown]]

[Federal Register: July 22, 1994]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-95-AD; Amendment 39-8980; AD 94-15-09]

 

Airworthiness Directives; Aerospatiale Model ATR72 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to all Aerospatiale Model ATR72 series airplanes. This 
action requires inspections to detect damage, corrosion, or cracking of 
the hinge pin on each shock absorber on the main landing gear (MLG), 
and repair or replacement of the pins, if necessary. This amendment is 
prompted by reports of rupture of certain hinge pins due to stress 
corrosion of the pins in the shock absorber on the MLG on Model ATR72 
series airplanes. The actions specified in this AD are intended to 
prevent loss of the MLG during a hard landing due to malfunction of the 
shock absorber on the MLG.

DATES: Effective August 8, 1994. The incorporation by reference of 
certain publications listed in the regulations is approved by the 
Director of the Federal Register as of August 8, 1994.
    Comments for inclusion in the Rules Docket must be received on or 
before September 20, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 94-NM-95-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056.
    The service information referenced in this AD may be obtained from 
Technical Publications Department, Messier-Eram, Zone Aeronautique Luis 
Breget, B.P. 10, 78142 Velizy Cedex, France. This information may be 
examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, 
SW., Renton, Washington; or at the Office of the Federal Register, 800 
North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Sam Grober, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-1187; fax (206) 227-1320.

SUPPLEMENTARY INFORMATION: The Direction Generale de l'Aviation Civile 
(DGAC), which is the airworthiness authority for France, recently 
notified the FAA that an unsafe condition may exist on all Aerospatiale 
Model ATR72 series airplanes. The DGAC advises that it has received 
reports of rupture of the upper hinge pins in the shock absorber on the 
main landing gear (MLG) on Model ATR72 series airplanes. Investigation 
revealed that these hinge pins ruptured due to stress corrosion inside 
the pin. Corrosion inside the hinge pins, if not detected and corrected 
in a timely manner, could result in malfunction of the shock absorber 
on the MLG. This condition, if not corrected, could result in loss of 
the MLG during a hard landing.
    Avions de Transport Regional (ATR) has issued Service Bulletin 
ATR72-32-1025, dated April 5, 1994. This service bulletin references 
Messier-Bugatti Service Bulletin 631-32-099, dated April 12, 1994, for 
additional service information. The Messier-Bugatti service bulletin 
describes procedures for repetitive visual inspections (using a 
borescope) to detect damage to the protective treatments on the inside 
diameter of the hinge pin on each shock absorber on the MLG. The 
service bulletin describes procedures for stripping any damaged 
protective treatments to determine if the base metal is corroded, 
completing a paint scheme of the damaged area, and reinstalling any pin 
on which no corrosion of the base metal is found. For pins on which the 
base metal is corroded, the service bulletin describes procedures for 
removal of the corrosion and a dye penetrant or fluorescent penetrant 
inspection to detect cracking of the pin; repair or replacement of any 
uncracked pin; and replacement of any cracked pin with a serviceable 
pin.
    The DGAC classified these service bulletins as mandatory and issued 
French Airworthiness Directive 94-065-020(B), dated March 30, 1994, in 
order to assure the continued airworthiness of these airplanes in 
France.
    This airplane model is manufactured in France and is type 
certificated for operation in the United States under the provisions of 
section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and 
the applicable bilateral airworthiness agreement. Pursuant to this 
bilateral airworthiness agreement, the DGAC has kept the FAA informed 
of the situation described above. The FAA has examined the findings of 
the DGAC, reviewed all available information, and determined that AD 
action is necessary for products of this type design that are 
certificated for operation in the United States.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design registered 
in the United States, this AD is being issued to prevent loss of the 
MLG during a hard landing. This AD requires repetitive visual 
inspections (using a borescope) to detect damage to the protective 
treatments on the inside diameter of the hinge pin on each shock 
absorber on the MLG. This AD also requires stripping any damaged 
protective treatments to determine if the base metal is corroded. For 
pins on which the base metal is not corroded, this AD requires 
completion of a paint scheme of the damaged area and reinstallation of 
the pin. For pins on which the base metal is corroded, this AD requires 
removal of the corrosion and a dye penetrant or fluorescent penetrant 
inspection to detect cracking of the pin; repair or replacement of any 
uncracked pin; and replacement of any cracked pin with a serviceable 
pin. The actions are required to be accomplished in accordance with the 
Messier-Bugatti service bulletin described previously.
    Messier-Bugatti advises that a modification of the link between the 
shock absorber and the universal joint is currently under study. 
Therefore, this AD is considered to be interim action until final 
action is identified, at which time the FAA may consider further 
rulemaking.
    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this rule by 
submitting such written data, views, or arguments as they may desire. 
Communications shall identify the Rules Docket number and be submitted 
in triplicate to the address specified under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the rule. All comments submitted will be 
available, both before and after the closing date for comments, in the 
Rules Docket for examination by interested persons. A report that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 94-NM-95-AD.'' The postcard will be date stamped and 
returned to the commenter.
    The regulations adopted herein will not have substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, may be obtained from the Rules Docket at the 
location provided under the caption ADDRESSES.
    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

List of Subjects in 14 CFR Part 39

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (14 CFR part 39) as follows:

Adoption of the Amendment

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

94-15-09 Aerospatiale: Amendment 39-8980. Docket 94-NM-95-AD.

    Applicability: All Model ATR72 series airplanes, certificated in 
any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent loss of the main landing gear (MLG) during a hard 
landing, accomplish the following:
    (a) Perform a visual inspection (using a borescope) to detect 
damage to the protective treatments on the inside diameter of the 
upper hinge pins on each shock absorber on the MLG, in accordance 
with Messier-Bugatti Service Bulletin 631-32-099, dated April 12, 
1994, at the time specified in paragraph (a)(1), (a)(2), or (a)(3) 
of this AD, as applicable. Repeat this inspection thereafter at 
intervals not to exceed 4,000 landings.
    (1) For airplanes on which the MLG has accumulated more than 
9,000 total landings as of the effective date of this AD: Inspect 
within 300 landings after the effective date of this AD.
    (2) For airplanes on which the MLG has accumulated 6,000 or more 
total landings but less than or equal to 9,000 total landings as of 
the effective date of this AD: Inspect prior to the accumulation of 
9,300 total landings, or within 1,000 landings after the effective 
date of this AD, whichever occurs first.
    (3) For airplanes on which the MLG has accumulated less than 
6,000 total landings as of the effective date of this AD: Inspect 
prior to the accumulation of 7,000 total landings, or within 3,000 
landings after the effective date of this AD, whichever occurs 
later.
    (b) If no damaged protective treatment is found, prior to 
further flight, reinstall the grease duct and fill the cavity 
between the pin and the grease duct with grease in accordance with 
Messier-Bugatti Service Bulletin 631-32-099, dated April 12, 1994. 
Thereafter, perform the repetitive inspections required by paragraph 
(a) of this AD.
    (c) If any damaged protective treatment is found, prior to 
further flight, strip the damaged protective treatment to determine 
if the base metal is corroded, in accordance with Messier-Bugatti 
Service Bulletin 631-32-099, dated April 12, 1994.
    (1) If no corrosion of the base metal is found, within 250 
landings, complete a paint scheme of the damaged area, reinstall the 
grease duct, and fill the cavity between the pin and the grease duct 
with grease in accordance with the service bulletin. Thereafter, 
perform the repetitive inspections required by paragraph (a) of this 
AD.
    (2) If any corrosion of the base metal is found, prior to 
further flight, remove the corrosion, and perform a dye penetrant or 
a fluorescent penetrant inspection to detect cracking of the pin, in 
accordance with the service bulletin.
    (i) If no crack is found, accomplish either paragraph 
(c)(2)(i)(A) or (c)(2)(i)(B) of this AD in accordance with the 
service bulletin. Thereafter, perform the repetitive inspections 
required by paragraph (a) of this AD.
    (A) Prior to further flight, repair the hinge pin; or
    (B) Within 50 landings after performing the inspection required 
by paragraph (c)(2) of this AD, replace the hinge pin with a 
serviceable pin.
    (ii) If any crack is found, prior to further flight, replace the 
hinge pin with a serviceable pin in accordance with the service 
bulletin. Thereafter, perform the repetitive inspections required by 
paragraph (a) of this AD.
    (d) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Standardization Branch, ANM-113, 
FAA, Transport Airplane Directorate. Operators shall submit their 
requests through an appropriate FAA Principal Maintenance Inspector, 
who may add comments and then send it to the Manager, 
Standardization Branch, ANM-113.

    Note: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Standardization Branch, ANM-113.

    (e) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.
    (f) The actions shall be done in accordance with Messier-Bugatti 
Service Bulletin 631-32-099, dated April 12, 1994. This 
incorporation by reference was approved by the Director of the 
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 
51. Copies may be obtained from Technical Publications Department, 
Messier-Eram, Zone Aeronautique Luis Breget, B.P. 10, 78142 Velizy 
Cedex, France. Copies may be inspected at the FAA, Transport 
Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or 
at the Office of the Federal Register, 800 North Capitol Street, 
NW., suite 700, Washington, DC.
    (g) This amendment becomes effective on August 8, 1994.

    Issued in Renton, Washington, on July 15, 1994.
S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-17766 Filed 7-21-94; 8:45 am]
BILLING CODE 4910-13-U